Original Goals and Specific Aims The Aquatic Models Core is a unique facility worldwide, equipped to conduct biomedical research using two of the most powerful aquatic research models -- rainbow trout and zebrafish. It is a self-contained fish hatchery for rearing fish and a histopathology complex for conducting tumor and toxicity studies. For the carcinogenesis and toxicity studies, investigators can choose several exposure routes, such as water-bath exposure of embryos or fry, dietary exposure, or embryo injection. The goal is to facilitate the short- and long-term experiments of Center investigators in several research cores by: Providing consultation to establish the suitability and feasibility of conducting studies in aquatic models; Providing high quality rainbow trout and zebrafish at multiple life stages; Providing technical core support including tank allocations, diet preparation and feeding; Providing assistance in selecting and performing chemical exposures; Providing specific expertise in surgery, necropsy, and histopathological evaluation; Working with the investigators in data acquisition and interpretation.